Cases with a failure to establish a block 30 minutes after local anesthetic injection will be considered as block failure and the patient will be excluded from the efficacy part of the study. These patients will receive intravenous patient controlled analgesia. Once the effectiveness and level of the block is confirmed the patient will be moved to the operating room for the surgery under standardized general anesthesia using fentanyl 2-3µg/Kg, propofol 2 mg/kg and rocuronium 0.8-1.0 mg/kg for intubation followed by maintenance with desflurane in air-oxygen mixture. Vasopressors (Ephedrine and phenylephrine) will be administered as needed to control hemodynamics and the total dose used will be recorded.